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Electromagnetic Induction/Transcript
Transcript Text reads: The Mysteries of Life with Tim and Moby. An animation shows Tim watching television. Moby walks into the room. The picture on the television is distorted and a rainbow shows up right next to the astronaut. TIM: Argh! I was just getting to the best part! An animation shows Moby grabbing the television. The picture on the television becomes even more distorted and starts to flicker. TIM: Dear Tim and Moby, how are electricity and magnetism related? From Innes. Just... just turn it off for now. Moby switches it off. TIM: Electricity and magnetism are really two sides of the same force: the electromagnetic force. Tim addresses the camera. Text reads: electromagnetic force. MOBY: Beep. TIM: Basically, that means that electricity can be converted to magnetism, and vice-versa. The connection between the two forces was originally detected in 1820 by a Danish chemist named Hans Orsted. An image shows a drawing of Hans Orsted from the shoulders up. The camera slowly pulls back, and text at the bottom right reads: Hans Orsted. TIM: He observed that a wire with electricity running through it would make a compass needle move. An animation shows a pair of hands. One hand is holding a compass with a needle pointing to "Upper N," the other hand is holding a wire. The hand holding the wire moves closer to the hand holding the compass. The compass needle moves from "Upper N" to "Upper W," and then fluctuates slightly. TIM: But he had no idea what this finding meant. The camera pulls back from the pair of hands to show Hans Orsted. Question marks appearing around his head. TIM: A decade later a British scientist named Michael Faraday built on Orsted's work. An image shows a drawing of Michael Faraday. The camera slowly pulls back, and text at the bottom right reads: Michael Faraday. TIM: Faraday correctly hypothesized that when an electric current runs through a wire, it creates a magnetic field around that wire. An animation shows a series yellow circles moving through a black wire against a purple. Three white circles of three different sizes appear around the wire, so the wire is going through the smallest, inner circle. TIM: This discovery led Faraday to believe that the opposite might be true: a magnetic field could create, or induce, an electric current in a wire. Text reads: induce. TIM: To prove it, he moved a magnet through a coil of wire; sure enough, an electric current was produced. He also found that the direction of the current changes depending on which way the magnet is moving. And the faster the magnet moves through the coil, the stronger the induced current. An animation shows a bar magnet moving down through a vertical coil of wire. The ends of the magnet are labeled "Upper N" and "Upper S." Once the magnet has completely moved through the wire, a small spark appears at the top of the coil. The magnet passes back up through the coil, and a small spark appears at the bottom of the coil. The magnet passes back down through the coil, more quickly this time, and a larger spark appears at the top of the coil. TIM: Meanwhile, the current running through the wire creates a magnetic field. An animation shows a coil of wire. Moving from the coil are overlapping, dotted lines that create oval shapes from the top to the bottom of the coil. TIM: The ability of magnets to create an electric current, and of electric currents to create magnetic fields, is called electromagnetic induction. The discovery of this relationship is considered one of the most important scientific developments in history! Text reads: electromagnetic induction. TIM: Electromagnetic induction is responsible for the widespread use of electricity in our world today. MOBY: Beep. TIM: Generators, machines that convert movement into electricity, use moving magnets to create a current. An image shows a farm scene. A gray cylindrical generator stands in the foreground. A wire is running from the generator to a barn and silo in the background. Text reads: generators. TIM: Electric motors do the opposite, converting electricity into mechanical motion. An image shows a hand holding a power drill. Text reads: electric motors. TIM: And transformers use induction to convert the strength of an electric current. An image shows two black cylinders with red stripes that represent transformers. The cylinder in the background has even black and red stripes, and the cylinder in the foreground had thick red stripes and thin black stripes. Text reads: transformers. TIM: That's how the high voltage current from the power station is converted into the lower voltage current your house uses. Four images are shown: a drawing of a large building, a drawing of four industrial powerlines in a row, a drawing of residential powerlines, and a drawing of a house. TIM: Last but not least, just about every electronic technology, from doorbells to airplanes, uses electromagnets, magnets created by electricity. An animation shows images of a doorbell, car, airplane, refrigerator, television, and a stereo appearing one at a time on the screen. Text reads: electromagnets. TIM: It'd be pretty hard to imagine a world where we didn't use electromagnetic induction. Tim uses a remote control to turn on the television. The television picture is distorted. TIM: Uh oh. Dad's gonna be really mad if that’s still there when he gets home. Category:BrainPOP Transcripts Category:BrainPOP Engineering & Technology Transcripts Category:BrainPOP Science Transcripts